Bus structure from aluminum reduction cells

ABSTRACT

The improvement in electrolytic cells for the reduction of aluminum in which a plurality of cells are electrically connected in a line, the improvement comprising diagonal bus structure for connecting to the cathode collector elements at the upstream side of the cell for directing current therefrom exteriorly of the cell diagonally to the opposite ends.

United States Patent Inventor Arthur F. Johnson 203 Creole Lane,Franklin Lakes, NJ. 07417 Appl. No. 876,128

Filed Nov. 12, 1969 Patented Nov. 2, 1971 BUS STRUCTURE FROM ALUMINUMREDUCTION CELLS 17 Claims, 5 Drawing Figs.

U.S. Cl .L 204/67, 204/243, 204/244 Int. Cl C22d 3/12, C22d 3/02 Fieldof Search 204/67, 243-247 [56] References Cited UNITED STATES PATENTS2,999,801 9/1961 Wleugel 204/244 3,063,919 11/1962 Jouguet et a1...204/244X Primary ExaminerJohn l-l. Mack Assistant Examiner-D. R.Valentine Attorney-Pennie, Edmonds, Morton, Taylor and Adams ABSTRACT:The improvement in electrolytic cells for the reduction of aluminum inwhich a plurality of cells are electrically connected in a line, theimprovement comprising diagonal bus structure for connecting to thecathode collector elements at the upstream side of the cell fordirecting current therefrom exteriorly of the cell diagonally to theopposite ends.

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INVENTOR. ARTHUR E JOHNSON wax/ 2% ATTORNEYS BACKGROUND OF THE INVENTIONIn my earlier US. Pat. No. 3,385,778, I disclose a currentcollectingsystem for an aluminum reduction cell in which the current from thecathode collector elements is collected at each side and each end of thecell and directed to exteriorly disposed bus structure encircling thecell. From there, the current is led to the anode of the next downstreamcell disposed in side by side relationship. In the constructiondisclosed in my earlier patent, the cathode collector elements aredivided into four sets. Two of these sets extend normally to the sidesof the cell; one set from the upstream side and the other from thedownstream side of the cell. The remaining two sets extend inwardly fromthe opposite two ends of the cell. The current in each of these-sets isled to the exterior bus structure through the walls from which theyextend. For example, the collector elements extending inwardly fromtheupstream side of the cell are connected to bus structure disposedexteriorly of the cell along this side. With the cell constructiondisclosed in my earlier patent, the collection of the current asdescribed above surpresses any electromagnetic stiring of the reducedmolten aluminum and lessens the resultingheaping of the aluminum. Themost harmful electromagnetic effects are experienced along the upstreamside of the cell and particularly at the upstream corn'ers where thevertical magnetic flux is at a maximum. With the invention disclosed inmy earlier patent, however, the current paths reduce the verticalmagnetic flux at the upstream corners of the cell andthus reduce thecurrents in the molten aluminum so as to lessen to about half thetendency of the molten aluminum to heap or circulate at these comers ofthe cell. This improves the operating efficiencies as well as the thermoand electrical efficiencies of the cell.

SUMMARY OF THE INVENTION In accordance with the teachings of the presentinvention, the concentration of the vertical magnetic flux as well asthe electromagnetic circulation and heaping at the upstream corners ofthe cell are further reduced from that found in the cell construction ofmy earlier patent. With the cell construction of the present invention,some or all of the current collected by the collector elements at theupstream side of the cell is fed exteriorly underneath the cell indiagonal paths toward the opposite ends of the cell. This, in turn,reduces or eliminates the current flowing around the upstream corners ofthe cell along exteriorly disposed bus structure. In addition, thecollector elements on the upstream side of the cell which are disposednear, one end of the cell are connected to bus structure which iselectrically separated from the bus structure for carrying current fromthe upstream collector elements at the other end of the cell. A similarseparation of the bus structure is provided on the downstream side ofthe cell so that current flow from one cell to the next in the line isfrom one localized quadrant of the cell to a similarly localizedquadrant of the next downstream cell. This construction limits theamount of current to any one anode of the cell and thus suppressescurrent variations in the individual anodes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top plan view of two cellsin side by side relationship with certain parts removed to show thecurrent collecting structure;

FIG. 2 is a vertical, cross section taken along lines 2-2 of FIG. 1 of afully constructed cell;

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1,two electrolytic cells of the Hall type for the electrolytic productionof aluminum are shown in side by side electrically connectedrelationship. For clarity and to avoid a duplication of the structurerepresented, certain parts of the cells are not shown in FIG. I. In FIG.2, however, a cross-sectional view of a fully constructed cell is shown.Each cell in the line is comprised of a rectangularshaped, open-toppedpotshell I having steel sides 2, 3, steel ends 4, 5 and steel bottom 6.The bottom and sides of the potshell are insulated with a granular orbrick-type refractory 7. A thinner refractory 8 is used for insulatingthe top deck 9 of the potshell. A carbon potlining 10 holds the cryolitefusion 11 and the underlying layer of molten aluminum I2. Two rows ofanode carbons 13 are suspended in the cryolite fusion by anode rods 14which receive current from an anode bus 15 suspended above the potshell.Steel cathode collector elements 16 are embedded in the carbon potliningfor collecting current and directing it outwardly of the potshell to thecathode bus structure generally-designated at 17. Flexible aluminum orcopper straps l8 connect the cathode collector elements to the cathodebus structure. The thinner refractory 8 is advantageously used forinsulating the collector elements where they extend through the walls ofthe potshell.

The potshell is supported on pairs of steel channel irons l9 welded orotherwise secured to the opposite sides of steel plates 20 as shown inFIG. 9 of my earlier patent. The channel irons are disposed underneaththe potshell and extend outwardly of its sides while the vertical steelplates abut against the sides of the potshell to restrain them fromexpanding and thus prevent heaving of the potlining. As shown in FIG. 2,the channel irons are supported on a concrete or refractory floor 21 tomaintain the potshell raised above the floor. In addition, the floor ischanneled at 22 directly underneath the potshell. This support allowscooling air to flow in underneath the potshell and then upwardly aroundthe sides. In addition, this support structure permits positioning ofthe bus structure in accordance with the teachings of the presentinvention as more fully described below.

In the embodiment of the invention shown in FIG. I, the cathodecollector elements 16 extend generally normal to -the sides of thepotshell. One set of side collector elements extends from the upstreamside 2 about half way to the downstream side while a second set,separate from the first set, extends from the downstream side 3 abouthalf way to the upstream side. In accordance with the teachings of thepresent invention, the bus structure for connecting at least some of theside collector elements on the upstream side of the potshell directs thecurrent in a diagonal path underneath the potshell to the opposite ends4 and 5 of the shell.

In the embodiment of FIG. 1, two diagonal buses 23, 24 are provided forconnection to the four-side collector elements on the upstream side ofthe potshell disposed most centrally between the ends of the potshell.The two collector elements 16a and 16b nearer the end 4 of the potshellare connected to the diagonal bus 23 while the two collector elements16a and 16b disposed nearer the end 5 of the potshell are connected tothe diagonal bus 24.

The construction of the diagonal bus 23 is most clearly shown in FIG. 3as comprising an elongated central section having upstanding portions ateither end. At one end. there are two upstanding portions 23a and 231)while at the other end there is a single upstanding portion 23c. Theportions 23a and 23!: are adapted to be connected to the collectorelements and 16b, respectively, at the point where they extend throughthe upstream side 2 of the potshell. The upstanding portion 23c isadapted to be connected to the bus structure at the downstream comer ofthe potshell for directing current to the anode of the next downstreamcell. The diagonal busses 23 and 24 are mirror images of each other.

In FIG. 2, the buss structure 24 is shown as extending exteriorly of thepotshell from the upstream side 2, underneath the bottom 6 of thepotshell to the end (hidden from view) where it is connected by theupstanding portion 24c to the external bus structure leading to the nextdownstream cell. The channel 22 in the refractory floor 21 provides roomfor the extension of the diagonal busses underneath the potshell.

The side-collector elements on the upstream side of the potshell whichare not connected to the diagonal buses are connected to cathode buses25-30. More particularly, the side-collector elements 16c and 16d areconnected to the bus 25, the collector elements 16c and 16f to the bus26, and the collector elements 16 16h, and 16i are connected to the bus27. Similarly, the. collector elements l6a-16i' nearer the other end 5of the potshell are connected to the buses 28, 29 and 30.

The bus structure 25, 26 and 27 is electrically separate from the busstructure 28, 29 and 30. The bus structure 25-27 extends around the end4 of the potshell toward the next cell in the potline while the busstructure 28-30 extends around the end Sin a similar fashion.

To complete the electrical connection of the collector elements to theexternal bus structure, the collector elements extending inwardly of thepotshell from the downstream side 3 are connected to downstream cathodebuses 31-34. With reference to FIG. I, the collector elements l6j, 16k,161 and 16m are connected to the bus 31 while the collector elementsl6n, I60, 16p, 16g and 16r are connected to the bus 32. Similarly, thecollector elements 16j'-l6r' are connected in the busses 33 and 34. Aswith the upstream bus structure, the buses 31 and 32 are electricallyseparate from the buses 33 and 34. The downstream bus structure joinsthe upstream bus structure at the downstream corners of the potshell.From there, all bus structure is directed to the anode structure of thenext downstream cell to maintain the electrical connection between thecells.

In order to limit the flow of current from one quadrant of the upstreamcell to. a similar quadrant of the downstream cell, the anode structureis brokeninto four separate sections and the cathode bus from eachquadrant of the cell 1 is connected to the section of the anodestructure 15 disposed over the corresponding quadrant of the nextdownstream cell. The quadrant separation of the bus structure of thecells together with the diagonal orientation of the buses 23 and 24limits the amount of current flowing around the upstream corners of eachcell and thus suppresses the magnetic activity at these corners tendingto cause heaping of the molten aluminum.

The diagonally disposed paths defined by the buses 23 and 24 togetherwith the associated buses 25-27 and 28-30 define triangular areas ateach upstream corner of the potshell. Accordingly, the current beingdirected along the diagonal buses 23 and 24 produces within thetriangular area at each corner of the potshell a vertical flux inopposition to the flux created by the current flowing through the buses25-27 and 28-30.

In addition to the limitations ofthe current flow at the upstreamcorners of the potshell, the diagonal bus structure and separation ofthe buses generally improve the operating effi- .-.....-..M.........1...Wswe cciency of the potshell by improving the ampere efficiency. Thisimprovement results because the current variations in each individualanode of the anode bus structure is suppressed by dividing the anode busstructureinto sections and thus limiting the current which is madeavailable to each anode. With conventional cells where the bus structureencircles the potshell, current variations in the individual anodes mayvary to a greater extent and thus decrease the ampere deficiency of thecell. This variation may occur, for example, when the anodes are new andset too low at one end of the cell. This would cause all availablecurrent to be drawn from the cathode bus disposed at the same end of theadjacent upstream cell. In addition, however, current would also bedrawn from the cathode bus at the opposite end of the adjacent upnec tedtogetherYAsaconsequenceigreater than one-fourth of the total amperagecan be drawn around either of the upstream comers of the cell resultingin intense magnetic activity, in turn, causing heaping bf the moltenaluminum.

A modified construction of the present invention is shown in FIG. 4.There, the orientation of the side-collector elements is the same as inthe construction shown in FIG. 1. Instead of the single pair of diagonalunderpot buses, however, a second pair 39, 40 is provided. These twoadditional buses 39 and 40 are connected, respectively, to the upstreamcollector elements 16c and 16d and and 16d. With this construction, moreof the current collected by the side-collector elements on the upstreamside of the potshell may be directed diagonally to the opposite ends ofthe potshell; and thus the current flowing around the upstream comers ofthe potshell is further reduced.

In FIG. 5, there is shown a construction in which all of the currentcollected along the upstream side of the potshell is directed diagonallyto the opposite ends of the potshell. In this construction, only sixcentrally disposed side-collector elements l6a-l6c, l6a-l6c, l6j-l6l and16j'-l6l' extend inwardly from the sides of the potshell. The threecollector elements l6a-l6c on the upstream side nearer the end 4 of thepotshell are connected to one diagonally extending underpot bus whilethe three collector elements l6a-l6c' nearer the end 5 are connected toa separate diagonal bus 42 extending toward that end of the potshell.For this purpose, each of the buses 41 and 42 has three upstandingportions designated by the suffix a, b and c, at the upstream side ofthe potshell. To connect these buses to the bus structure at thedownstream corners of the potshell, the upstanding portions 41d and 42dare provided.

In the construction shown in FIG. 5, a plurality of end collectorelements 44, 45 are provided in place of the upstream side collectorelements 1611-16! and I6d'-l6i' and the downstream side-collectorelements 16m-16r and 16m '-l6r' found in the embodiment of FIG. 1. Theseend collector elements 44 and 45 extend inwardly from either end of thepotshell and are connected directly to end bus elements 46, 47 and 48,49. The latter bus elements replace the bus elements 25-27 and 28-30 ofthe construction shown'in FIG. 1. It will be seen that with theconstruction of FIG. 5, all current flow around the upstream corners ofthe potshell is eliminated. Accordingly, electromagnetic stiring andthus circulation and heaping of the molten aluminum at these upstreamcorners are greatly reduced.

The above description of the present invention has been made withrespect to the preferred embodiments thereof. However, it is to beunderstood that various changes may be made without departing from thescope of the invention as set forth in the following claims.

I claim:

1. In an electrolytic cell for the reduction of aluminum having arectangular potshell adapted to be disposed in a line of electrolyticcells in electrically connected side by side relationship and having anelectrically conductive cathode potlining and a plurality ofside-cathode collector elements extending generally normal to the sidesof the potshell and in electrical engagement with said potlining, and acurrent carrying bus structure disposed cxteriorly of said potshell. forcarrying current from its cathode collector elements to the anode of thenext downstream cell in said line of cells, the improvement wherein saidbus structure includes an underpot bus section connected on the upstreamside of said potshell to the side collector elements disposed centrallyof the ends of said potshell and extending diagonally underneath saidpotshell to the opposite ends thereof for connection to the anode of thenext downstream cell.

2. The improvement in an electrolytic cell according to claim 1 whereinthe underpot bus section includes two separate buses, each of whichextends diagonally underneath the potshell to one of the opposite endsthereof.

3. The improvement in an electrolytic cell according to claim 2 whereineach of the diagonal buses are connected on the upstream side of thepotshell to a plurality of said side-collector elements disposedadjacent a different end of the potshell.

4. The improvement in an electrolytic cell according to claim 3 whereinthe collector elements extending normal to the sides of the potshellinclude one set extending from the upstream side thereof toward thedownstream side and of which at least some are connected to saiddiagonal buses; and a second set, separate from the first set, extendingfrom the downstream side of said potshell toward the upstream side.

5. The improvement in an electrolytic cell according to claim 4 whereinthe collector elements of the second set are connected to a downstreambus extending externally of said potshell on the downstream sidethereof.

6. The improvement in an electrolytic cell according to claim 5 whereina plurality of parallel extending diagonal buses are disposed underneathsaid potshell for connecting to the side-collector elements on theupstream side of said potshell.

7. The improvement in an electrolytic cell according to claim 5 whereinsaid bus structure includes exteriorly disposed end buses disposed alongthe ends of the potshell and end-collector elements extending from andnormal to each of said ends to a point less than half the length of saidpotshell, said end-collector elements at each end of the potshell beingconnected to the end bus at that end.

8. The improvement in an electrolytic cell according to claim 7 whereinall of the side-collector elements of said one set are connected to saiddiagonal buses.

9. The improvement in an electrolytic cell according to claim 5 whereinthe downstream bus includes two sections each of which extends from oneof the forward corners toward each other with one section beingconnected to the collector elements of the second set disposed adjacentone end of the potshell and the other section being connected to thecollector elements disposed adjacent the other end of the potshell.

10. The improvement in an electrolytic cell according to claim 9 whereinthe downstream bus and diagonal buses are joined at the downstreamcorners of the potshell for leading to the next downstream cell in saidline.

ll. In the process of electrolytically reducing aluminum in arectangular potshell adapted to be disposed in a line of electrolyticcells in electrically connected side by side relationship and having anelectrically conductive cathode potlining and a plurality of sidecathode collector elements extending generally normal to the sides ofthe potshell and in electrical engagement with said potlining, and acurrent carrying bus structure disposed exteriorly of said potshell andconnected to said side collector elements for carrying current from saidcollector elements to the anode of the next downstream cell in said lineof cells, the improvement of collecting current from the plurality ofsaid collector elements at the upstream side of said potshell anddirecting said current exteriorly below said potshell along diagonalpaths to the opposite ends thereof for feeding to the anode of the nextdownstream cell.

12. The improvement in the process according to claim 11 wherein thecurrent in the side collector elements nearer one end of said potshellis directed along one of said diagonal paths to the one end of saidpotshell and the current in the collector elements nearer the other endis directed in a second diagonal path to the other end of said potshell.

13. in the process according to claim 12 wherein the collector elementsextending normal to the sides of the potshell include one set extendingfrom the upstream side thereof toward the downstream side and a secondset, separate from said first set, extending from the downstream sidetoward the upstream side, the improvement wherein the current in aplurality of collector elements of said first set is collected at theupstream side of said potshell'and directed along said diagonal pathsand the current in the collector elements of said second set iscollected at the downstream side of said potshell and directedexteriorly of said potshell along the downstream side thereof for feedinto the anode of the next downstream cell in said line.

14. n the process according to claim 13 wherein end-collector elementsextend from and normal to each of the ends of said potshell to a pointless than half the length thereof. the improvement wherein the currentin the end collector elements at each end of the potshell is connectedat that end and directed exteriorly of said potshell along that end forfeeding to the anode of the next downstream cell in said line.

15. The improvement in the process according to claim 14 wherein thecurrent in all of the collector elements of said one set is collected atthe upstream side of said potshell and fed exteriorly along saiddiagonal paths to the ends of said potshell.

16. The improvement in the process according to claim 13 wherein thecurrent in the collector elements of said second set nearer one end ofsaid potshell is directed separately of the current in the collectorelements of the second set nearer the other end of the potshell to theanode of the next downstream cell.

17. The improvement in the process according to claim 16 wherein thecurrent collected in each quadrant of said potshell is fed to thecorresponding quadrant of the next downstream cell.

2. The improvement in an electrolytic cell according to claim 1 whereinthe underpot bus section includes two separate buses, each of whichextends diagonally underneath the potshell to one of the opposite endsthereof.
 3. The improvement in an electrolytic cell according to claim 2wherein each of the diagonal buses are connected on the upstream side ofthe potshell to a plurality of said side-collector elements disposedadjacent a different end of the potshell.
 4. The improvement in anelectrolytic cell according to claim 3 wherein the collector elementsextending normal to the sides of the potshell include one set extendingfrom the upstream side thereof toward the downstream side and of whichat least some are connected to said diagonal buses; and a second set,separate from the first set, extending from the downstream side of saidpotshell toward the upstream side.
 5. The improvement in an electrolyticcell according to claim 4 wherein the collector elements of the secondset are connected to a downstream bus extending externally of saidpotshell on the downstream side thereof.
 6. The improvement in anelectrolytic cell according to claim 5 wherein a plurality of parallelextending diagonal buses are disposed underneath said potshell forconnecting to the side-collector elements on the upstream side of saidpotshell.
 7. The improvement in an electrolytic cell according to claim5 wherein said bus structure includes exteriorly disposed end busesdisposed along the ends of the potshell and end-collector elementsextending from and normal to each of said ends to a point less than halfthe length of said potshell, said end-collector elements at each end ofthe potshell being connected to the end bus at that end.
 8. Theimprovement in an electrolytic cell according to claim 7 wherein all ofthe side-collector elements of said one set are connected to saiddiagonal buses.
 9. The improvement in an electrolytic cell according toclaim 5 wherein the downstream bus includes two sections each of whichextends from one of the forward corners toward each other with onesection being connected to the collector elements of the second setdisposed adjacent one end of the potshell and the other section beingconnected to the collector elements disposed adjacent the other end ofthe potshell.
 10. The improvement in an electrolytic cell according toclaim 9 wherein the downstream bus and diagonal buses are joined at thedownstream corners of the potshell for leading to the next downstreamcell in said Line.
 11. In the process of electrolytically reducingaluminum in a rectangular potshell adapted to be disposed in a line ofelectrolytic cells in electrically connected side by side relationshipand having an electrically conductive cathode potlining and a pluralityof side cathode collector elements extending generally normal to thesides of the potshell and in electrical engagement with said potlining,and a current carrying bus structure disposed exteriorly of saidpotshell and connected to said side collector elements for carryingcurrent from said collector elements to the anode of the next downstreamcell in said line of cells, the improvement of collecting current fromthe plurality of said collector elements at the upstream side of saidpotshell and directing said current exteriorly below said potshell alongdiagonal paths to the opposite ends thereof for feeding to the anode ofthe next downstream cell.
 12. The improvement in the process accordingto claim 11 wherein the current in the side collector elements nearerone end of said potshell is directed along one of said diagonal paths tothe one end of said potshell and the current in the collector elementsnearer the other end is directed in a second diagonal path to the otherend of said potshell.
 13. In the process according to claim 12 whereinthe collector elements extending normal to the sides of the potshellinclude one set extending from the upstream side thereof toward thedownstream side and a second set, separate from said first set,extending from the downstream side toward the upstream side, theimprovement wherein the current in a plurality of collector elements ofsaid first set is collected at the upstream side of said potshell anddirected along said diagonal paths and the current in the collectorelements of said second set is collected at the downstream side of saidpotshell and directed exteriorly of said potshell along the downstreamside thereof for feeding to the anode of the next downstream cell insaid line.
 14. In the process according to claim 13 whereinend-collector elements extend from and normal to each of the ends ofsaid potshell to a point less than half the length thereof, theimprovement wherein the current in the end collector elements at eachend of the potshell is connected at that end and directed exteriorly ofsaid potshell along that end for feeding to the anode of the nextdownstream cell in said line.
 15. The improvement in the processaccording to claim 14 wherein the current in all of the collectorelements of said one set is collected at the upstream side of saidpotshell and fed exteriorly along said diagonal paths to the ends ofsaid potshell.
 16. The improvement in the process according to claim 13wherein the current in the collector elements of said second set nearerone end of said potshell is directed separately of the current in thecollector elements of the second set nearer the other end of thepotshell to the anode of the next downstream cell.
 17. The improvementin the process according to claim 16 wherein the current collected ineach quadrant of said potshell is fed to the corresponding quadrant ofthe next downstream cell.